Sous vide problems

I've been experimenting with sous-vide cooking for some time now, but despite general enthusiasm, my results are not really that perfect.
I'm goal is a perfect steak. And I tried it a number of times - I always set the temperature to 53-57 degrees Celsius, season the meat with salt and pepper generously, seal, and keep in the water bath for 1-3 hours. And the problem is that the meat always ends up grayish, often dry. Usually good and edible, but still not the perfect medium or medium-rare I would expect.
I tried a number of things. First of all I checked the temperature. In the beginning I was using home-made sous-vide machine, now I'm using SousVide Supreme and they both show the same, proper temperature, which I additionally check with two different hand-held thermometers (both calibrated at 0C and 100C). And one day I accidently forgot to turn the mashine on, and just left a steak in the hot tap water. It was lying 2 hours, the temperature dropped from 45C to 39C but the meat was still grayish in the middle.
I though that maybe is the packing process that is faulty. I always used ziplock bag submerging method. But recently I discovered ziplock bags that come with a hand held pump. And while the packaging looks much better, the result is still the same.
Today I though that maybe that's seasoning fault - maybe excessive amount of salt on the meat drags out the juices during cooking. So I tried to cook two pieces of the same steak, side by side, one salted before. And of course, they were exactly the same. Exactly the same medium-well.
Here are some photos from my today experiments:

And while there is some pink in those photos (it looked much worse in reality) but there is none of that juicy redness I was expecting. And when pressed, the meat was becoming totally grey.
Any ideas anyone?